package apple2 import ( "fmt" "image" "image/color" "image/png" "os" ) /* References: - "Understanding the Apple II", http://www.applelogic.org/files/UNDERSTANDINGTHEAII.pdf - "Apple II Reference Manual" - "More Colors for your Apple", https://archive.org/details/byte-magazine-1979-06/page/n61 */ // Snapshot the currently visible screen func Snapshot(a *Apple2) *image.RGBA { isColor := a.isColor isTextMode := a.io.isSoftSwitchActive(ioFlagText) isHiResMode := a.io.isSoftSwitchActive(ioFlagHiRes) isMixMode := a.io.isSoftSwitchActive(ioFlagMixed) pageIndex := 0 if a.io.isSoftSwitchActive(ioFlagSecondPage) { pageIndex = 1 } var lightColor color.Color if isColor { lightColor = color.White } else { // Color for typical Apple ][ period green P1 phosphor monitors // See: https://superuser.com/questions/361297/what-colour-is-the-dark-green-on-old-fashioned-green-screen-computer-displays lightColor = color.RGBA{65, 255, 0, 255} } var snap *image.RGBA if isTextMode { snap = snapshotTextMode(a, pageIndex, false, lightColor) } else { if isHiResMode { snap = snapshotHiResModeMonoShift(a, pageIndex, isMixMode, lightColor) } else { snap = snapshotLoResModeMonoShift(a, pageIndex, isMixMode, lightColor) } if isMixMode { snapText := snapshotTextMode(a, pageIndex, isMixMode, lightColor) snap = mixSnapshots(snap, snapText) } if isColor { snap = filterNTSCColor(false /*blacker*/, snap) } } snap = linesSeparatedFilter(snap) return snap } func mixSnapshots(top, bottom *image.RGBA) *image.RGBA { topBounds := top.Bounds() topWidth := topBounds.Dx() topHeight := topBounds.Dy() bottomBounds := bottom.Bounds() bottomWidth := bottomBounds.Dx() bottomHeight := bottomBounds.Dy() factor := topWidth / bottomWidth size := image.Rect(0, 0, topWidth, topHeight+bottomHeight) out := image.NewRGBA(size) // Copy top for y := topBounds.Min.Y; y < topBounds.Max.Y; y++ { for x := topBounds.Min.X; x < topBounds.Max.X; x++ { c := top.At(x, y) out.Set(x, y, c) } } // Copy bottom, applyng the factor for y := bottomBounds.Min.Y; y < bottomBounds.Max.Y; y++ { for x := bottomBounds.Min.X; x < bottomBounds.Max.X; x++ { c := bottom.At(x, y) for f := 0; f < factor; f++ { out.Set(x*factor+f, topHeight+y, c) } } } return out } // SaveSnapshot saves a snapshot of the screen to a png file func SaveSnapshot(a *Apple2, filename string) error { img := Snapshot(a) img = squarishPixelsFilter(img) f, err := os.Create(filename) if err != nil { return err } defer f.Close() png.Encode(f, img) return nil } func squarishPixelsFilter(in *image.RGBA) *image.RGBA { b := in.Bounds() factor := 1200 / b.Dx() fmt.Println(factor) size := image.Rect(0, 0, factor*b.Dx(), b.Dy()) out := image.NewRGBA(size) for x := b.Min.X; x < b.Max.X; x++ { for y := b.Min.Y; y < b.Max.Y; y++ { c := in.At(x, y) for i := 0; i < factor; i++ { out.Set(factor*x+i, y, c) } } } return out } func linesSeparatedFilter(in *image.RGBA) *image.RGBA { b := in.Bounds() size := image.Rect(0, 0, b.Dx(), 4*b.Dy()) out := image.NewRGBA(size) for y := b.Min.Y; y < b.Max.Y; y++ { for x := b.Min.X; x < b.Max.X; x++ { c := in.At(x, y) out.Set(x, 4*y, c) out.Set(x, 4*y+1, c) out.Set(x, 4*y+2, c) out.Set(x, 4*y+3, color.Black) } } return out }